Enhanced Virtual Addressing

Enhanced Virtual Addressing (EVA) is a particular configuration of the Segmentation Control registers to extend the user virtual address space up to 3 GiB (overlapping the traditional placement of kseg0 and kseg1) while also extending the kernel address space down to zero so that it has 3 GiB unmapped and 1 GiB mapped.

Due to the overlap of user/kernel virtual address space, various new instructions are provided for performing user memory operations from kernel mode, which the kernel uses for accessing when it needs to access userland memory.